I'm bumping this thread one last time.
I have finished my PXE loader (no thanks to any of the emulators...)
I have used 3 different BIOSes for each of the virtual cards on both Bochs and Qemu, no matter how I slice it I cannot get past TFTP Open
And because my code is completed I'll post the full source of all PXE functions:
Code: Select all
%ifndef __PXEBASEAPI_INC__INCLUDED__
%define __PXEBASEAPI_INC__INCLUDED__
[bits 16]
PXE_GET_CACHED_INFO equ 0x0071
PXE_TFTP_OPEN equ 0x0020
PXE_TFTP_READ equ 0x0022
PXE_TFTP_CLOSE equ 0x0021
; NOTE THESE ARE NOT REGISTER SAFE!
init_PXE:
mov cx, 22; 44/2
mov di, PXEENV
mov si, bx
.copyPXEENV:
mov ax, WORD [es:si]
mov WORD [ds:di], ax
add si, 2
add di, 2
dec cx
jnz .copyPXEENV
cmp WORD [PXEENV.Version], 0x0201
jge .NewerPXE
mov ax, WORD [PXEENV.RMEntryOffset]
mov WORD [PXEAPIOffset], ax
mov ax, WORD [PXEENV.RMEntrySegment]
mov WORD [PXEAPISegment], ax
jmp .Contine
.NewerPXE:
push es
mov ax, WORD [PXEENV.PXEPtrSegment]
mov es, ax
mov si, WORD [PXEENV.PXEPtrOffset]
mov di, PXE
mov cx, 12; 24/2
.copyPXE:
mov ax, WORD [es:si]
mov WORD [ds:di], ax
add si, 2
add di, 2
dec cx
jnz .copyPXE
pop es
mov ax, WORD [PXE.RMEntryOffset]
mov WORD [PXEAPIOffset], ax
mov ax, WORD [PXE.RMEntrySegment]
mov WORD [PXEAPISegment], ax
.Contine:
mov bx, PXE_GET_CACHED_INFO
mov di, PXENV_GET_CACHED_t
call usePXE
test ax, ax
mov ax, WORD [PXENV_GET_CACHED_t]
jnz TFTP_ERROR
mov ax, WORD [PXENV_GET_CACHED_t.BufferSeg]
mov bx, WORD [PXENV_GET_CACHED_t.BufferOff]
push es
mov es, ax
mov eax, DWORD [es:bx + 16]
mov DWORD [ClientIP], eax
mov eax, DWORD [es:bx + 20]
mov DWORD [ServerIP], eax
mov eax, DWORD [es:bx + 24]
mov DWORD [RelayIP], eax
pop es
ret
;ds:si = filename
TFTP_OPEN:
push si
mov eax, DWORD [ServerIP]
mov DWORD [PXENV_TFTP_OPEN_t.SIP], eax
mov eax, DWORD [RelayIP]
mov DWORD [PXENV_TFTP_OPEN_t.GIP], eax
mov di, PXENV_TFTP_OPEN_t.Filename
.SetFileName:
lodsb
test al, al
mov BYTE [ds:di], al
jz .FNDone
inc di
jmp .SetFileName
.FNDone:
mov ax, 69
xchg al, ah
mov WORD [PXENV_TFTP_OPEN_t.Port], ax ; tftp udp port number !!!BIGENDIAN!!!
mov WORD [PXENV_TFTP_OPEN_t.PacketSize], 0x200 ; 512 byte packets
mov di, PXENV_TFTP_OPEN_t
mov bx, PXE_TFTP_OPEN
call usePXE
pop si
test ax, ax
jnz .ERROR
ret
.ERROR:
mov ax, WORD [PXENV_TFTP_OPEN_t.Status]
jmp TFTP_ERROR
TFTP_CLOSE:
mov di, PXENV_TFTP_CLOSE_t
mov bx, PXE_TFTP_CLOSE
call usePXE
test ax, ax
mov ax, WORD [PXENV_TFTP_CLOSE_t.Status]
jnz TFTP_ERROR
ret
;ds:di = buffer
;RET AX = PACKET SIZE RECIVED
TFTP_READ_PACKET:
mov WORD [PXENV_TFTP_READ_t.BufferOff], di
mov WORD [PXENV_TFTP_READ_t.BufferSeg], ds
mov di, PXENV_TFTP_READ_t
mov bx, PXE_TFTP_READ
call usePXE
test ax, ax
jnz .ERROR
mov ax, WORD [PXENV_TFTP_READ_t.BufferSize]
ret
.ERROR:
mov ax, WORD [PXENV_TFTP_OPEN_t.Status]
jmp TFTP_ERROR
; DS:DI = PACKET
; BX = PXE Opcode
usePXE:
push ds
push di
push bx
call far [PXEAPI]
add sp, 6
ret
;input ax = error code
TFTP_ERROR:
push ERROR.halt ; Push return address.
cmp ax, 0x01
je .PXEE01
cmp ax, 0x32
je .PXEE32
cmp ax, 0x35
je .PXEE35
cmp ax, 0x36
je .PXEE36
cmp ax, 0x38
je .PXEE38
cmp ax, 0x39
je .PXEE39
cmp ax, 0x3A
je .PXEE3A
cmp ax, 0x3B
je .PXEE3B
cmp ax, 0x3C
je .PXEE3C
cmp ax, 0x3F
je .PXEE3F
mov si, TFTP_ERROR_CODES.PXEExx
call puts
jmp PrintHex
.PXEE01:
mov si, TFTP_ERROR_CODES.PXEE01
jmp puts
.PXEE32:
mov si, TFTP_ERROR_CODES.PXEE32
jmp puts
.PXEE35:
mov si, TFTP_ERROR_CODES.PXEE35
jmp puts
.PXEE36:
mov si, TFTP_ERROR_CODES.PXEE36
jmp puts
.PXEE38:
mov si, TFTP_ERROR_CODES.PXEE38
jmp puts
.PXEE39:
mov si, TFTP_ERROR_CODES.PXEE39
jmp puts
.PXEE3A:
mov si, TFTP_ERROR_CODES.PXEE3A
jmp puts
.PXEE3B:
mov si, TFTP_ERROR_CODES.PXEE3B
jmp puts
.PXEE3C:
mov si, TFTP_ERROR_CODES.PXEE3C
jmp puts
.PXEE3F:
mov si, TFTP_ERROR_CODES.PXEE3F
jmp puts
PXEENV:
.Signiture db 0, 0, 0, 0, 0, 0
.Version dw 0
.Length db 0
.CheckSum db 0
.RMEntry:
.RMEntryOffset dw 0
.RMEntrySegment dw 0
.PMOffset dd 0
.PMSelector dw 0
.StackSeg dw 0
.StackSize dw 0
.BCCodeSeg dw 0
.BCCodeSize dw 0
.BCDataSeg dw 0
.BCDataSize dw 0
.UNDIDataSeg dw 0
.UNDIDataSize dw 0
.UNDICodeSeg dw 0
.UNDICodeSize dw 0
.PXEPtr:
.PXEPtrOffset dw 0
.PXEPtrSegment dw 0
PXE:
.Signiture db 0, 0, 0, 0
.Length db 0
.CheckSum db 0
.Revision db 0
.Reserved db 0
.UNDIROMID dd 0
.BCROMID dd 0
.RMEntry:
.RMEntryOffset dw 0
.RMEntrySegment dw 0
.PMEntry dd 0
PXENV_GET_CACHED_t:
.Status dw 0
.PacketType dw 3
.BufferSize dw 0x1000
.BufferOff dw 0x1000
.BufferSeg dw 0
.BufferLimit dw 0
PXENV_TFTP_OPEN_t:
.Status dw 0
.SIP dd 0
.GIP dd 0
.Filename times 128 db 0
.Port dw 0
.PacketSize dw 0
PXENV_TFTP_READ_t:
.Status dw 0
.PacketNumber dw 0
.BufferSize dw 0
.BufferOff dw 0
.BufferSeg dw 0
PXENV_TFTP_CLOSE_t:
.Status dw 0
PXEAPI:
PXEAPIOffset dw 0
PXEAPISegment dw 0
ClientIP dd 0
ServerIP dd 0
RelayIP dd 0
TFTP_ERROR_CODES:
.PXEE01 db "PXE-E01: TFTP error - File not found. or Access violation.", 0
.PXEE32 db "PXE-E32: TFTP open timeout.", 0
.PXEE35 db "PXE-E35: TFTP read timeout.", 0
.PXEE36 db "PXE-E36: Error received from TFTP server.", 0
.PXEE38 db "PXE-E38: TFTP cannot open connection.", 0
.PXEE39 db "PXE-E39: TFTP cannot read from connection.", 0
.PXEE3A db "PXE-E3A: TFTP too many packages.", 0
.PXEE3B db "PXE-E3B: TFTP error - File not found.", 0
.PXEE3C db "PXE-E3C: TFTP error - Access violation.", 0
.PXEE3F db "PXE-E3F: TFTP packet size is invalid.", 0
.PXEExx db "UNKNOWN ERROR! ", 0
%endif
And the strap I use to actually read the file into memory
Code: Select all
%ifndef __TFTP_INC__INCLUDED__
%define __TFTP_INC__INCLUDED__
[bits 16]
TFTP_ReadFile:
pusha
db 0x66
push edx
push si
mov si, LOADMSG
call puts
pop si
call puts
mov DWORD [FileSize], 0
call TFTP_OPEN
.ReadLoop:
mov si, WAITMSG
call puts
mov di, 0x1000
call TFTP_READ_PACKET
db 0x66
xor ecx, ecx
mov cx, ax
db 0x66
pop edx
db 0x66
mov edi, edx
db 0x66
push edx
db 0x66
xor eax, eax
mov ax, WORD [PXENV_TFTP_READ_t.PacketNumber]
dec ax
db 0x66
xor edx, edx
mov dx, WORD [PXENV_TFTP_OPEN_t.PacketSize]
db 0x66
mul edx
db 0x66
add edi, eax
db 0x66
push ecx
db 0x66
mov esi, 0x1000
call memcpy
db 0x66
pop ecx
add DWORD [FileSize], ecx
cmp cx, WORD [PXENV_TFTP_OPEN_t.PacketSize]
je .ReadLoop
call TFTP_CLOSE
db 0x66
pop edx
mov si, DONEMSG
call puts
popa
mov eax, DWORD [FileSize]
ret
LOADMSG db "Loading TFTP File ", 0
FileSize dd 0
%endif
So, all source interfacing the BootROM is provided.
Can anyone explain how to get the emulators to function properly?
I really do not want to fix (rewrite) my disk boot loader (this week, maybe next) - I improved upon a lot of the osloader and changed the Kernel's requirements - plus my (realmode) FAT driver is an error waiting to happen (using 32-bit values to start the math - then only using 16-bit arithmetic)
It is very difficult, though not impossible, to debug on real hardware. I miss watching my register values and everything else
But the good news (at least for me) is I now know my scheduler, IPC, and memory management work properly on real hardware. No triple faults, no random lockups, and everything ran as programmed for the whole duration on 5 different systems.
NOTE TO ANYONE WHO USES PXE:
Not all hardware will return its "negotiated" packet size on TFTP_OPEN, it will remain what you requested, though may be set to 0x200 (512 bytes) without informing you!
<- wish I knew about that one sooner... I might even get FAT32 and FAT16 in the same boot sector...
, worked like a charm (same result in hex, but cleaner for sure)